I don't know the exact number of artificial Earth satellites, but it is probably a few thousand objects. Some are communications satellites, or military spy satellites. There is one large telescope (Hubble), one space station (Mir), and sometimes various other manned spacecraft (shuttles or Soyuz craft) in orbit. However, the majority of the objects orbiting the Earth are "space junk" -- spent rocket boosters, satellites which did not achieve the proper orbit, and so on.

There are over 100,000 man made objects in orbit around the Earth.The vast majority of them are junk: small pieces of old spacecraft in various sizes. The rest are satellites for military and commercial use. A big problem right now is that all this space junk can collide with and damage the shuttle or expensive satellites. How do you think we could get rid of it cheaply and efficiently?

I heard back from the Navy officer who works in Cheyenne Mountain. He says that objects larger than about 10 cm across can be tracked from the earth. The exact number known changes daily, but as of Friday, March 13 that number was 8,060. The previous day it was 8,063. About 7% of those objects are active payloads - communications satellites, and probably a fair number of spy satellites. (Some of the objects in orbit are kept secret, too, so this probably isn't the whole story.)And of course, the Mir space station and periodically the space shuttle. The remaining 93% are "junk" - dead satellites (their batteries run out after a few years, and the solar panels can only recharge them for so long), rocket bodies, and debris (I'm guessing that much of the debris results from collisions between larger pieces of space junk orbiting the earth.)